The use of latch needles for forming loops has long been favored to permit a simple loop-forming process. Such a needle is disclosed, for example, in U.S. Pat. No. 3,453,845. The latch needle has a shank which, at one end, has a hook, in front of which a sawslot is formed. A latch, which serves for opening and closing the hook, projects with one end into the sawslot and is pivotally supported therein. The latch may pivot into a closed position in which it lies against the hook tip with its latch spoon. For opening the hook, the latch may swing into its reverse position in which it is pivoted to the farthest possible from the hook and in which it lies on the shank or is disposed at least adjacent thereto.
The sawslot is, as a rule, of throughgoing construction, that is, it is open toward the needle back. Independently therefrom, dirt accumulating in the sawslot may adversely affect the operation.
Further, for example, German Patent No. 586,678 discloses a latch needle, whose sawslot is configured in a special manner for reducing its tendency to become soiled. The sawslot widens from a constriction toward both the needle breast and the needle back. The enlargement extends both in the length direction and in the transverse direction of the needle. By virtue of such a funnel-shaped enlargement toward the needle back, an accumulation of dirt is intended to be prevented or at least reduced, since dirt may more easily leave the sawslot.
In latch needles having freely movable latches, the latter may, due to rebounds or other external effects, assume an undefined position. To avoid such occurrences, latch needles provided with a spring-loaded latch have been developed. Such a latch needle is disclosed in German Patent Document DE-AS 1,113,537. The latch needle has a sawslot which widens toward the needle breast relative to the longitudinal direction of the shank. Toward the needle back the sawslot is bounded by parallel flanks. In the narrow, divergent sawslot surfaces oriented toward needle breast, spring-supporting pockets are formed for receiving the ends of a latch spring formed as a leaf spring. The latch spring is introduced into the sawslot at the needle breast, and is threaded into its desired position by means of an auxiliary tool introduced into the sawslot. The underside of the spring lies against the spring-supporting pockets and its upper side lies against the end of the latch.
For such a basic construction the sawslot must have a relatively large volume for allowing the latch spring to be threaded in. Further, the latch spring is only moderately secured in the spring-supporting pockets in the depth of the sawslot. The latch spring may slip and/or may become lost, and, as a result, the needle does no longer operate correctly.
It is therefore an object of the invention to provide an improved latch needle.